U11B2: Multi-Manufacturer: U11B0-U11B7 (CMU CAN Timeout)

Description

U11B0-U11B7 indicate Mitsubishi EV/hybrid battery cell monitoring unit CAN timeout. Check CMU modules, wiring, and BMU communication.

Common Symptoms

• FOR MITSUBISHI EV/HYBRID: Reduced electric range, loss of power, warning lights related to battery system, possible "Service Hybrid System" message
• FOR OTHER VEHICLES: Varies by manufacturer - requires make-specific diagnosis

Possible Causes

• FOR MITSUBISHI: Faulty CMU module, damaged harness/connectors in local CAN bus, BMU (SUB) failure, CAN line harness damage [citation:3]
• BMU (SUB) power supply voltage out of range (should be 8-16V) [citation:3]
• Unable to receive battery sensor module signals through CAN bus for 1+ second [citation:3]

Diagnosis Steps

1. IDENTIFY MANUFACTURER FIRST - This range has specific Mitsubishi EV/hybrid meanings.
2. FOR MITSUBISHI: Use M.U.T.-III scan tool to check for other DTCs, especially P1AD3-P1ADD series [citation:3].
3. Check IGCT, GND, CANH, CANL lines between CMU connector and main drive lithium-ion battery connector for damage [citation:3].
4. Remove battery tray cover and inspect CMU modules.
5. If wiring is OK, suspect failed CMU or BMU (SUB) [citation:3].
6. Perform OBD-II Drive Cycle Pattern 1 test after repairs [citation:3].

Repair Solutions

• FOR MITSUBISHI: Repair damaged CAN bus wiring/harness between CMU and battery connector [citation:3]
• Replace faulty CMU module (specific to code U11B0-U11B7)
• Replace sub-battery management unit [BMU (SUB)] if CMU communication fails [citation:3]
• Assemble main drive lithium-ion battery assembly per service manual procedures

Prevention Tips

• Always verify manufacturer and model before diagnosing U11B0-U11B7 codes
• For Mitsubishi EVs/hybrids, follow factory service manual high-voltage safety procedures
• Check BMU power supply voltage first - must be 8-16V [citation:3]